What is the reason the view isn't rotated around the selected object?
Go in Edit mode and select all, as you can see you've accidentally created a vertice far from the origin point of your mesh, it completely moves the rotation centre of your 3D view (as the Rotate Around Selection option, in the User Preferences, seems to consider the Geometry Origin, not the current origin of the object, as its pivot point):



In Object mode, if you selected this object, you weren't able to see this vertice, it looks like you can see edges and faces (surrounded by an orange line) but not isolated vertex.